In order to protect an occupant in the driver's seat or the passenger seat in a collision or an emergency of a vehicle, cars with an airbag device, which has an inflatable and deployable airbag, installed in, for example, the steering wheel or the instrument panel are widely used. Furthermore, in recent years, in order to further enhance the function of protecting an occupant, including an occupant who is seated in the rear seat, side-surface side airbag devices that deploy an airbag (a so-called curtain-like airbag) in a curtain-like manner along a side window inside the vehicle so as to cover the entirety thereof are also known (see Patent Document 1).
In the airbag device disclosed in Patent Document 1, the airbag is attached to a roof rail portion or the like on the side of the vehicle such that the airbag is inflated and deployed with gas from an inflator so as to blocks an opening in the vehicle and cover the vehicle wall, thereby protecting mainly the head of the occupant in the front seat or the rear seat. Furthermore, this airbag device uses a cylinder-type inflator, in which a metal guide tube (guide tube portion) is fixed to the outer circumference of its cylindrical main body so as to enclose a plurality of gas discharge ports at one end, an opening in the guide tube at the tip is inserted into the airbag, and the inflator is attached to a gas inlet of the airbag. The airbag device guides gas discharged radially, for example, from the gas discharge ports to an inner tube in the airbag by the guide tube and supplies the gas into the airbag through them, thereby inflating and deploying the airbag.
Herein, typically, the gas inlet of an airbag is formed by sewing edges of a base fabric constituting the airbag into a tubular shape, into which one end of the inflator is inserted together with a guide tube and is fixed from the outside by fixing means, whereby the inflator is attached to the gas inlet. Accordingly, in such a conventional airbag device, the guide tube also serves to protect the airbag by reducing the pressure of the gas discharged from the gas discharge ports of the inflator or by preventing the gas from being directly jetted against the base fabric. Therefore, in order to ensure these functions, typically, a metal member is used as the guide tube, as described above.
However, such a metal guide tube requires high manufacturing cost. In addition, because it needs to be fixed to the outer circumference of the inflator by caulking, the time and effort required to attach the metal guide tube to the inflator tend to be high. This results in problems in that the manufacturing cost of airbag devices increases and that the structure around the inflator becomes complex. Accordingly, it is required that gas is supplied into the airbag from the gas discharge ports while the airbag is assuredly protected from the radially discharged gas, without providing a metal guide tube enclosing the plurality of gas discharge ports of the inflator, unlike in the case of the conventional airbag device.
Furthermore, for example, if a fire breaks out during transportation, storage, or the like of an airbag device, the metal guide tube does not burn and remains fixed to the inflator. If the inflator is activated in this state, the gas discharged radially from the gas discharge ports is discharged from the opening at one end of the guide tube in the direction of the opening. By this, a driving force acts on the inflator, causing the inflator to be thrown into the air, which increases the risk.
[Patent Document 1]                the Publication of Japanese Patent No. 3689845        